Individual careers have been transformed by new ways of working within organizations and beyond, and specifically the imposition of market models on employment, the intensification of competition, and flexible employment contracts. As a result, the study of job mobility (i.e., individuals changing jobs within or between organizations) and career transitions (i.e., how the change is understood and managed by individuals and organizations) has become an increasingly important subject of study, with causes and implications that span multiple disciplines and subfields of management, such as careers, human resources management, organization theory, organizational behavior, and strategy. Although the roots of academic inquiry into job mobility and career transitions go back to the beginning of modern management studies, the past twenty years have seen an upsurge in these studies, enabled by new data sources (e.g., online resumes) and methods (e.g., text analysis and big data methods) that track individual careers, as well as recognition that job mobility and career transitions are important social phenomena. See also the separate Oxford Bibliographies in Management article “Career Studies” by Yehuda Branch, especially the section on Contemporary Careers. The perspective of this article is primarily based in careers and organizational studies, but other Oxford Bibliographies in Management articles that cover related phenomena from different theoretical perspectives are “Turnover” by Peter Hom; “Human Capital Resource Pipelines” by Anthony Nyberg, Dhuha Abdulsalam, and Ingo Weller; and “Strategic Human Capital” by Rhett Brymer, Janice Molloy, and Clint Chadwick.